Located in Hạ Long and Bái Tá»­ Long are archaeological sites such as Mê Cung and Thiên Long. There are remains from mounds of mountain shellfish (Cyclophorus), spring shellfish (Melania), some fresh water mollusc and some rudimentary labour tools. The main way of life of Soi Nhụ's inhabitants included catching fish and shellfish, collecting fruits and digging for bulbs and roots. Their living environment was a coastal area unlike other Vietnamese cultures, for example, like those found in Hoà Bình and Bắc SÆ¡n. (Soi Nhụ culture (16,000- 5000 BC)

Cái Bèo culture (5000- 3000 BC)

Located in Hạ Long and Cát Bà island, its inhabitants developed to the level of sea exploitation.

Feudal period

History shows that Hạ Long Bay was the setting for local naval battles against Vietnam's coastal neighbors. On three occasions, in the labyrinth of channels in Bach Dang river near the islands, the Vietnamese army stopped the Chinese from landing. In 1288, General Tran Hung Dao stopped Mongol ships from sailing up the nearby Bach Dang River by placing steel-tipped wooden stakes at high tide, sinking the Mongol Kublai Khan's fleet.

During the Vietnam War, many of the channels between the islands were heavily mined by the United States navy, some of which pose a threat to shipping to this day.

Geology and geomorphology

History of tectonics

Hạ Long Bay has experienced at least 500 million years in various geological states of orogeny, marine transgression and marine regression. During the Ordovician and Silurian periods (500-410 million years ago), Hạ Long Bay was deep sea. During the Carboniferous and Permian periods (340-250 million years ago), Hạ Long Bay was at shallow sea level.

Karst geomorphology value

Due to a simultaneous combination of ideal factors such as thick, pale, grey, and strong limestone layers, which are formed by fine-grained materials; hot and moist climate and slow tectonic process as a whole; Hạ Long Bay has had a complete karst evolution for 20 million years. There are many types of karst topography in the bay, such as karst field.

Timeline of geologic evolution

Some of the most remarkable geological events in Hạ Long Bay’s history have occurred in the last 1,000 years, include the advance of the sea, the raising of the bay area, strong erosion that has formed coral, and, pure blue and heavily salted water. This process of erosion by seawater has deeply engraved the stone, contributing to its fantastic beauty. Present-day Hạ Long Bay is the result of this long process of geological evolution that has been influenced by so many factors.

Due to all these factors, tourists visiting Hạ Long Bay are not only treated to one of the natural wonders of the world, but also to a precious geological museum that has been naturally preserved in the open air for the last 300 million years.